Mount Sidley

Mount Sidley rises in Marie Byrd Land, Antarctica, the highest of five volcanoes forming the Executive Committee Range, reaching an elevation of about 4,285 meters. It is a massive, largely snow-covered shield volcano and the tallest of the Volcanic Seven Summits, the highest volcano on each continent. Its summit holds a distinctive caldera roughly 5 kilometers wide on the southern side, the collapse structure left after the volcano's magma chamber emptied during past eruptions. The mountain sits within the wider Marie Byrd Land Volcanic Province and is currently dormant. It went undiscovered until Rear Admiral Richard E. Byrd spotted it from an airplane on November 18, 1934, and it was not climbed until January 11, 1990, when New Zealander Bill Atkinson made the first recorded ascent while supporting a United States Antarctic Program expedition. This entity documents Mount Sidley specifically as a geological formation, a dormant shield volcano and the tallest of the Volcanic Seven Summits.